A camel-back fleece laying machine which has a laying arm, over which card web transport belts are guided, is described in EP 1 612 306 A1. A bottom end of the laying arm is connected to a carriage, which is guided transversely to the transport direction of an output conveyor belt, thus traveling back and forth above the belt. Two deflecting rolls, around each of which a cover belt passes, are rotatably mounted in the carriage. The lower run of each of these belts extends just above the output conveyor belt, and the upper run is parallel to, and a certain distance away from, the lower run. The deflecting rolls mentioned are a suitable distance apart, so that the cover belts on the deflecting rolls form a laying gap, through which the fiber card web coming from an output gap at the lower end of the laying arm is guided onto the output conveyor belt. The carriage is divided into two sleds, an upper sled and a lower sled. The bottom end of the laying arm is supported in the upper sled, whereas the previously mentioned deflecting rolls are supported in the lower sled. The upper sled can be adjusted to a slight extent with respect to the lower sled in the direction of movement of the carriage and also in the opposite direction, so that, within the carriage, the route which the card web describes can be changed in such a way as to reduce the danger that, when the carriage reverses its direction, the card web will enter a triangular pocket formed between the deflecting roll of one of the card web transport belts running along the laying arm, namely, the roll located in front with respect to the direction of movement, and the deflecting roll of one of the cover belts, namely, the roll situated, again, in front with respect to the direction of movement. The two sleds thus oscillate to a slight extent with respect to each other during the laying cycle.
As the carriage oscillates back and forth across the output conveyor belt, it arrives at the edges of the output conveyor belt, which represent the endpoints of its path. The carriage must be braked to zero at these points, and after reversing direction, it must be accelerated again. This variation in the speed of the carriage must be brought into harmony with the uniform speed with which the card web to be laid is supplied to the fleece laying machine by a carding machine, for otherwise there will be thick areas at the edges of the fleece laid by the fleece laying machine. The fleece laying machine described in the previously mentioned EP 1 612 306 A1 therefore has a web buffer in its infeed area. Because of its location, this buffer is called the infeed web buffer, and it takes up the excess length of card web material or pays it out again when the card transport belts running along the laying arm, which travel at the same speed as the carriage, start to travel at a speed which differs from that at which the carding machine, which operates at a uniform rate, is supplying the card web to the fleece laying machine. The volume of buffered card web in the infeed buffer area thus increases when the carriage is in a deceleration phase then decreases again after the carriage reverses direction and is in an acceleration phase.
The web buffer in the infeed area of the fleece laying machine makes the machine much more expensive, because a large number of deflecting rolls and moving parts are required to form this web buffer. In addition, the moving masses which must be braked and accelerated again by the drive units of the carriage are relatively large, which leads to corresponding loads and to premature wearing-out of the toothed belts used in these drive units.